Method for making sheet material split-ring lock washers



1959 J. B. O'CONNOR 2,867,824

METHOD FOR MAKING" SHEET MATERIAL-SPLIT-RING LOCK WASHERS Filed-May 4,1955 INVENTOK- @mZUCam dZvw/W;

United States Patent METHOD FOR MAKING SHEET MATERIAL SPLIT-RING LOCKWASHERS John B. OConnor, Glenview, lll., assignor to Illinois Thepresent invention relates to a novel method for producing lock washers,and more particularly to a novel method for producing split-ring typelock washers from a continuous strip of sheet material.

It has heretofore been proposed to manufacture splitring type lockwashers by stamping them from sheet material or by coiling a wire or rodand subsequently severing convolutions of the coil. One disadvantage ofthe lock Washers formed in accordance with such prior methods is thattheir holding power rapidly diminishes after they have beensubstantially flattened between a workpiece and a clamping member suchas a nut or screwhead.

To overcome this disadvantage, it has been proposed to provide a sheetmaterial split-ring lock washer having double compressibility or, inother words, a lock washer which ma for example, have a body which ishelically twisted and which has a radial cross sectional shape such thatit may be collapsed whereby the washer may be compressed by flatteningthe helix and also by flattening the radial cross sectional shape of thebody.

An important object of the present invention is to provide a novelmethod for producing a lock washer having double compressibility from anelongated strip of sheet material in a rapid, continuous and economicalmanner, and in a manner which substantially eliminates waste of sheetmaterial stock.

A more specific object of the present invention is the provision of anovel method for continuously producing from a strip of substantiallyflat sheet material a splitring lock washer which has a helicallytwisted body, and which body has a folded or axially collapsible radialross sectional shape so as to provide the washer with materiallyimproved locking characteristics.

A further object of the present invention is to provide a novel methodfor forming lock washers of the above described type from a continuousnarrow strip of sheet material, by which method ends of'the formedwashers are broken from the end of the strip easily and withoutsubstantially deforming or bending such ends during separation. D

Other objects and advantages of the present nvention will becomeapparent from the following description and the accompanying drawingswherein:

Fig. 1 is a diagrammatic elevational view showing an apparatus foraccomplishing'thenovel method of this invention;

Fig. 2 is a diagrammatic plan view of the apparatus shown in Fig. l;

Fig. 3 is a perspective view showing a section of an elongated flatsheet material strip to be formed mto washers in accordance with thepresent invention;

Fig. 4 is a fragmentary perspective view showing how the flat elongatedstrip may be scored so that the subsequently formed washers may beeasily separated;

Fig. 5 is a fragmentary perspective view showing a sectiOn of theelongated strip at an intermediate stage of its formation into washers;

Fig. 6 is a fragmentary perspective view showing a Patented Jan. 13,1959 section of the elongated sheet material strip in a foldedcondition;

Fig. 7 is an elevational view showing how the folded elongated strip iscoiled in accordance with the present invention;

Fig. 8 is an elevational view showing a lock washer formed in accordancewith the method of this invention; and

Figs. 9 through 12 are fragmentary plan views respectively showingdifferent methods of scoring the elongated sheet material strip so thatthe subsequently formed washers may be easily broken apart withoutbending or deforming the ends of the washers.

Referring now more specificially to the drawings wherein like parts aredesignated by the same numerals throughout the various figures, a lockwasher 20 formed in accordance with the method of the present inventionis shown in Fig. 8.. The lock washer is in the form of a split-ringwhich is helically twisted in the manner shown. In addition, the body ofthe washer is folded so that it includes upper and lower flanges 22 and24 joined by a curved Web portion 26, whereby to provide the washer bodywith a generally U-shaped radial cross section. When the washer 20 isclamped between a workpiece and a nut or a screwhead, the helical twistof the washer will first be flattened out so that the inherentresiliency of the sheet material provides a force tending to preventunauthorized retrograde movement or loosening of the nut or screw. Afterthe helical twist of the washer has been substantially flattened,further tightening of the nut or screw causes the flanges 22 and 24 tocollapse axially toward each other and causes further flexing of the webportion 26, and .as a result, the inherent resiliency of the sheetmaterial provides a further force tending to lock the nut or screwagainst retrograde movement.

In accordance with the present invention the method for producing lockwashers such as the washer 20 includes the steps of feeding a continuousstrip 28 of sheet material from a source of supply, continuously formingor folding the fiat strip along longitudinally extending mid-portionsthereof to provide opposed longitudinally extending marginal flanges,continuously coiling the advancing formed strip, and separatingconvolutions of the coil from each other to provide individual washers.The strip of sheet material i preferably sheet metal and is ofsubstantially uniform thickness and width throughout its length. Thestrip is formed and helically coiled while it is relatively soft, andafter the coiling operation has been completed, the washers areheat-treated to provide them with the desired resiliency.

Figs. 1 and 2 diagrammatically show an apparatus 30 for carrying out themethod of the present invention. More specifically, the strip 28 ofsheet metal is fed from a reel 32 to means 34 for continuously formingthe strip to provide it with the desired cross sectional shape. In theapparatus illustrated, the means 34 comprises a plurality of sets ofrollers which are continuously driven by suitable means not shown. Thefirst set of rollers 36 are preferably feed rollers. Succeeding sets ofrollers are formed so as to fold the strip progressively from. the fiatcondition shown in Figs. 3 and 4 through the partially folded conditionshown in Fig. 5 to the folded condition shown in Fig. 6. It will beappreciated that the number of sets of forming rollers may be increasedor decreased in accordance with requirements dictated by the sheetmaterial stock being formed. The formed strip of sheet material iscontinuously drawn from the rolling means 34 into a coiling mechanism 38which may be of any known construction capable of forming the strip intoa helical coil 40 as shown in Figs. 2 and 7.

After the strip has been coiled, the coil may be directed to a mechanism42 of known construction which is adapted to sever the'convolutions ofthe coil from each other. However, in accordance with another feature of1 the present invention, the strip is preferably scored in a mannerwhich causes each helically formed convolution to break away from thestrip substantially automatically during the coiling operation. Thisenables the severing mechanism 42 to be eliminated. "In Figs. 1 and 2there is shown punch press means 44 for scoring the sheetmaterial stripas indicated generally at 46 in Fig. 4. As will be understood, the punchpress is intermittently actuated in timed relationship with respect 'tothe feed rolls so that successive scores on the strip are spaced adistance slightly less than the circumferential extent of each of thesubsequently formed coil convolutions. When the intermittently operatedpunch press 44 is used to score the strip, means, not shown, is providedfor maintaining a loop 48 in the sheet material strip between therolling means and the punch press as shown in broken lines in 3 it isstill flat, and the set of rollers 50 of the rolling means 34 may beconveniently adapted to act as scoring'rollers.

It has been found that when the strip is provided with scores such asthe score 46 shown in Fig. 4, the pointed portions 52 and 54 of the endsof the strip to be separated may be bent or twisted as the ends arebroken apart. In

accordance with another feature of this invention, the strip may bescored as shown in Figs. 9 through 12 so as to prevent the separatedends of the strip from becoming bent or twisted while they are beingbroken apart. More lspecifically, Fig. 9 shows how recesses 56 and 58may be punched from the strip 28 at opposite ends of the score line 46so as to eliminate the above described pointed portions 52 and 54 andprovide the ends of the strip to be separated with relatively broad tipswhich are not easily deformed.

In Fig. the strip is provided with a diagonal score .line 60 and shorttransverse score lines 62 and 64 respec- :tively merging with oppositeends of the score line 60.

This arrangement also causes the ends of the strip to be separated tohave relatively broad tips which are not easily deformed. In addition,the score lines 62 and 64 may be formed deeper than the score line 60 soas further to promote a clean break between the ends of the strip.

In the above described method for scoring the strip, identical scorelines are provided in opposing relationship in opposite surfaces ofthestrip. In Fig. 11, however, the strip is provided with short diagonalscore lines 66 and 68 on one side and a long diagonal score line 70 onits opposite side, which long score line overlaps the short score linesbut terminates within the longitudinal margins of the strip.Furthermore, the long score line 70 is formed in the surface of thestrip which subsequently provides the outer surface of a helicalconvolution. Since the outer surface of the strip is stretched as thestrip is coiled as well as while the strip is being folded, the locationof the score line 70 causes the break to initiate at a mid-portion ofthe strip and progress outwardly toward the margins. This breakingaction substantially reduces or eliminates undesirable bending ortwisting of the separated end corners.

Fig. 12 shows another method of scoring the strip so that the strip willbreak from mid-portions toward its marginal edges. In this embodimentthe strip is completely slit or severed as at 72 and scores 74 and 76extend from opposite ends of the slit to the edges of the strip.

From the above description it is seen that the present invention hasprovided a novel method whereby splitring lock washers having doublecompressibility characteristics may be rapidly and economicallyproduced. More specifically, it is seen that the present invention haspro'. vided a novel method wherein the lock Washers are continuouslyformed from an advancing strip of sheet metal rapidly and substantiallywithout waste of the sheet metal stock. It is further seen that thepresent invention has provided a method wherein the sheet metal strip isscored so that the subsequently formed washers will break apart easilyand without having their ends. bent or twisted.

While the preferred embodiments ;of the present invention have beenshown and describedherein, it is obvious that many changes may be madewithout departing from the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A substantially scrapless method for manufacturing sheet materiallock washers having a split annular body and split annular marginalflanges extending inwardly in opposing spaced relationship, comprisingcontinuously advancing an elongated strip of sheet material ofsubstantially uniform thickness along a predetermined path of travel,successively scoring said strip along substantially equally spaced linesextending obliquely to the longitudinal axis of the strip for providingpredetermined lines along which the strip is subsequently broken whileproviding junctures between adjacent sections of the strip which resistunintentional breaking, the distance between said score lines beingequal to the circumferential meas urement of a finished washer article,then longitudinally folding the advancing strip to provide the stripwith a central body portion and opposite spaced marginal flanges,subsequently helically coiling the advancing strip so that said flangesextend inwardly and each convolution carries a score mark, andthen'breaking the strip along each of said obliquely extending scorelines.

2. A method, as defined in claim 1, which includes the step of providingmarginal recesses at opposite ends of each of the oblique scores beforethe strip is coiled .to facilitate the subsequent separation of adjacentconvolutions along the scores without substantial bending'of endportions of the convolutions.

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